Nicene and Post-Nicene Fathers, Vol. V:A Treatise on the Spirit and the Letter.: Chapter 30

Now, observe how consonant this diversity is with those words of the apostle which I quoted not long ago in another connection, and which p. 96I postponed for a more careful consideration afterwards: “Forasmuch,” says he, “as ye are manifestly declared to be the epistle of Christ ministered by us, written not with ink, but with the Spirit of the living God; not in tables of stone, but in fleshy tables of the heart.” 836
See how he shows that the one is written without man, that it may alarm him from without; the other within man himself, that it may justify him from within. He speaks of the “fleshy tables of the heart,” not of the carnal mind, but of a living agent possessing sensation, in comparison with a stone, which is senseless. The assertion which he subsequently makes,—that “the children of Israel could not look stedfastly on the end of the face of Moses,” and that he accordingly spoke to them through a veil, 837
—signifies that the letter of the law justifies no man, but that rather a veil is placed on the reading of the Old Testament, until it shall be turned to Christ, and the veil be removed;—in other words, until it shall be turned to grace, and be understood that from Him accrues to us the justification, whereby we do what He commands. And He commands, in order that, because we lack in ourselves, we may flee to Him for refuge. Accordingly, after most guardedly saying, “Such trust have we through Christ to God-ward,” 838
the apostle immediately goes on to add the statement which underlies our subject, to prevent our confidence being attributed to any strength of our own. He says: “Not that we are sufficient of ourselves to think anything as of ourselves; but our sufficiency is of God; who also hath made us fit to be ministers of the New Testament; not of the letter, but of the spirit: for the letter killeth, but the spirit giveth life.” 839